Petal Fall Stage Research Articles

Predicting Floral Bud Progression for Three Peach Cultivars

The prediction of floral bud progression in commercial peach cultivars promotes knowledge about the adaptability of cultivars to the climatic conditions in a specific location under a climatic variability context. Phenology is relevant to improving the scheduling of cultural practices in peach orchards. This research aimed to predict the floral bud progression of three peach cultivars: ‘Harvester’, ‘Red Globe’, and ‘Rubyprince’. Floral bud progression was assessed using one-year-old shoots collected from an orchard located at the Chilton Research and Extension Center, Alabama. Samples were evaluated under laboratory and growth chamber conditions. We recorded the flower developmental stages daily to identify the transition among stages. Daily temperature records were used to estimate the heat requirement in terms of Growing Degree Days (GDD). After dormancy release, samples needed between 23 to 39 and 37 to 42 days to reach the petal fall stage for season 1 and season 2, respectively. In terms of heat requirements, cultivars needed between 425.5 to 721.5 and 684.5 to 777 GDD to end flowering. A logistic curve was adjusted to describe the growth of the different floral stages over time. The results are key to supporting peach growers in crop management practices such as orchard establishment, irrigation, fertilization, freeze and frost protection, and pollination under climate variability scenarios.

Citrus black spot intensity and yield losses on sweet orange are affected by Phyllosticta citricarpa inoculum concentration and fruit developmental stage

AbstractCitrus black spot (CBS) symptom expression on sweet oranges has been reported to be affected by the fruit developmental stage and inoculum concentration in greenhouse conditions. However, there is little information concerning the period in which the fruit is susceptible in commercial orchards. This study assessed the influence of fruit age and inoculum concentration of Phyllosticta citricarpa on CBS intensity and fruit drop in the field. Two field trials were conducted in commercial ‘Valencia’ orchards in São Paulo state, Brazil. Fruit were inoculated from October (petal fall stage) to July (c.6.5 cm diameter), with 101, 103 and 105 pycnidiospores/ml. CBS symptoms and fruit drop were observed in higher levels for fruit inoculated from October to February than from March to July. In both trials, when fruit were inoculated 10 times from October to July or single‐inoculated in November or December, high CBS severities of 11%–22% were observed and the proportion of fruit remaining on the tree was 48%–77%; in contrast, noninoculated fruit had severity below 1.1% and 90% remained on the tree. Inoculations in November or December of green fruit with 1.5–3.0 cm diameter using 105 pycnidiospores/ml were associated with higher CBS intensity and fruit drop and shorter incubation period than inoculations with lower concentrations. This work provides a better understanding of fruit stages and P. citricarpa inoculum concentrations most related to symptom expression and losses under natural conditions and may be helpful for improvement of CBS management in the São Paulo citrus belt.

Role of Lygus hesperus (Hemiptera: Miridae) Adult Feeding on Deformation of Blackberry Fruits

Role of <i>Lygus hesperus</i> (Hemiptera: Miridae) Adult Feeding on Deformation of Blackberry Fruits

Apple Fruit Core Rot Agents in Greece and Control with Succinate Dehydrogenase Inhibitor Fungicides.

Core rot is a major postharvest disease of apple fruit that occurs worldwide and is caused by a complex of fungi. Despite the importance of the disease, little is known about its etiology in Greece. In this study, 325 fungal isolates obtained from fruit with core rot symptoms were identified to the species level using morphological characteristics and phylogenetic analysis. Fungal identification revealed that Alternaria alternata was the major disease agent (57.8% of the isolates), followed by Kalmusia variispora (27.8%), Botrytis cinerea (12%), and Fusarium spp. (3.3%). K. variispora is reported for the first time as an agent of core rot of apple and its pathogenicity was confirmed by artificial inoculation tests. In addition to disease etiology, field experiments were performed at two different orchards for 3 consecutive years (2017 to 2019). Experiments were conducted to determine the effectiveness of several classes of fungicides and the timing of application for control of the disease. Greater efficacy was achieved when fungicides were applied at the petal fall stage (flowers fading BBCH 67), while the most effective fungicides were the succinate dehydrogenase inhibitors fluxapyroxad, fluopyram, adepidyn, and penthiopyrad. The results of this study are expected to contribute to the optimization of disease management and reduce the yield losses caused by core rot pathogens in Greece.

Effects of GA4+7+BA and CPPU on russeting and fruit quality in apple (Malus × domestica)

Apple (Malus × domestica Borkh.) production is now being affected by the changing climate which has led to reduction in quality thereby, these fruits command low returns in the market. As it is the most important temperate fruit crop of Himachal Pradesh, it still requires a great improvisation in quality. The present study was conducted in 2017-18 with various plant growth regulator practices on eight year old apple trees cv. ‘Scarlet Spur II’. Application of GA4+7+BA at 2.5 and 5 ppm when given at petal fall and two times later at 10 days interval recorded minimum russet formation (Score:1.17), increased fruit length (68.93 mm) as well as increased L/D ratio (1.07), TSS and sugar content in apple. However, CPPU at 10 ppm when applied at petal fall stage recorded higher fruit diameter (70.89 mm), fruit weight (155.56 g), fruit volume (102.94 cc), TSS (10.72 ºBrix), total sugars (9.11%) and reducing sugars (4.87%).

Influence of prohexadione-calcium and paclobutrazol on growth, yield and mineral content of pear cv. Clapp&amp;#8217;s favourite

Present investigation was carried out to study the influence of growth retardants viz., prohexadione-calcium and paclobutrazol on mineral content of pear cv. ‘Clapp’s Favourite’ during the year 2015-2016. The experiment was laid out with thirteen treatments, replicated thrice on 12 year-old-pear tree with uniform vigor and health under uniform cultural practices. The treatment comprised of single and double spray of growth retardants i.e., prohexadione-calcium (100 ppm, 200 ppm and 300 ppm) and paclobutrazol (100 ppm, 200 ppm and 300 ppm). The first spray of these growth retardants was given at complete petal fall stage and second at four weeks after first spray. The orchard soil was moderately deep with good fertility status. Results revealed that both the growth retardants had showed a significant influence on the studied characters. The plants sprayed twice with prohexadione-calcium @ 200 ppm (T9S2) recorded minimum annual shoot extension growth of 16.92 cm and leaf area (22.20 cm2) alongwith increase in fruit yield (51.24 kg). Highest value for calcium (Ca) in leaves and fruits of pear (574.00 mg & 71.24 mg, respectively) was recorded when plants were sprayed twice with prohexadione-calcium at 300 ppm. Results also revealed that application of prohexadione-calcium application at 200 ppm sprayed twice (T9S2) resulted in significant increased in potassium content of the pear leaves and fruits i.e. 98.40 mg and 22.78 mg, respectively. However minimum value for potassium content was recorded in control (T1S0). Double spray of prohexadione-calcium @ 200 ppm was effective in reducing the annual extension growth, leaf area and increasing the fruit yield and calcium and potassium content in leaves and fruit.

Investigations on the Timing of Fruit Infection by Fungal Pathogens Causing Fruit Rot of Deciduous Holly.

Fruit rot of deciduous holly is an emerging fungal disease that is affecting plant production across midwestern and eastern U.S. nurseries. To determine the growth stage(s) of host susceptibility to infection by the major pathogens associated with the disease, Alternaria alternata and Diaporthe ilicicola, and minor pathogens such as Colletotrichum fioriniae and Epicoccum nigrum, we conducted two sets of experiments over two consecutive seasons. In the first case we monitored the presence of the pathogens as well as disease progression in a commercial nursery under natural conditions by collecting plant tissues from the flower bud stage until fruit maturity. The target pathogens were consistently isolated from asymptomatic samples at all stages of fruit development and from symptomatic samples at fruit maturity across the 2 years of collection. A significant increase in fungal isolation frequency, primarily species of Alternaria and Colletotrichum, was observed right after flowering, but fruit rot symptoms only developed on mature fruit. In the second case we artificially inoculated containerized plants maintained outdoor at our research farm with individual or combined pathogens at different fruit developmental stages, and we assessed disease incidence on mature fruit to determine the time of host susceptibility to infection and, indirectly, whether pathogens in the fungal complex carry out latent infections. D. ilicicola could cause latent infection on deciduous holly fruit when inoculated at the full bloom and petal fall stages, and all inoculations made on wounded mature fruit resulted in fruit rot. These findings suggest that flowering represents a critical period to manage D. ilicicola infections and that mature fruit should be protected from any injury to avoid disease. In both experiments a negative correlation between disease incidence and temperature was found; however, the decrease in temperature also coincided with fruit ripening. The effects of temperature and changes in physiological properties of the fruit during maturation on disease development should be further investigated to fully interpret these findings.

Pollination of kiwifruit: 30 years of applied research leads to a model system for studying the interaction between pollination and flowering stage

Kiwifruit vine artificial pollination was firstly studied in New Zealand and in Italy in the 80s in order to optimize the kiwifruit fruit set and production. Nowadays it is a crucial technique useful to increase fruit quality and size. However, artificial pollination efficiency depends on the timing of application and the pollination system. The main objective of this study is to decipher the relation between the floral stage and the pollination technique. Many parameters were analyzed in different environments in Italy for many years, such as pollen quality (germinability, humidity, conservation), pollination system (dry or liquid) and flowering stage. The petals fall and full bloom-early petal fall stages result in the best moments for dry and liquid pollination respectively. The dry blower pollination system gave the best results because, at the end of flowering, the pistil exudate is at its maximum and a larger number of ovaries are receptive with respect to the liquid pollination at full bloom. This observation leads to the definition of a new model crop fruit set that could be applied in other anemophilous pollinated tree such as olive tree, hazelnut, pistachio.

Response of prohexadione calcium and paclobutrazol on growth and physio-chemical characteristics of pear cv. Clapp's Favorite

The present investigation was conducted to study the response of growth retardants on pear cv. Clapp's Favorite during the year 2015–2016. The experiment was laid out with thirteen treatments replicated thrice on 12 year-old-trees with uniform vigour and health under uniform cultural practices. The treatment comprises of single spray and double spray of growth retardants (prohexadione calcium @ 100, 200 and 300 ppm and paclobutrazol @ 100, 200 and 300 ppm). The first spray of growth retardants was applied at petal fall stage and second spray was four weeks after first spray. The plants sprayed twice with prohexadione calcium @ 200 ppm (T9S2) recorded minimum annual shoot extension growth (16.92 cm), internodal length (1.82 cm) and leaf area (22.20 cm2) along with increase in fruit set (18.34%) and minimum fruit drop (32.45%). Increased fruit yield (51.24 kg), yield efficiency (4.08) and following year return bloom (24.04%) was noticed in T9S2 treatment. Prohexadione calcium sprayed twice @ 200 ppm (T9S2) also increased fruit weight (82.85 g), TSS (13.21%) and total sugars (10.23%) closely followed by the double spray of prohexadione calcium @ 300 ppm sprayed twice which was also effective in enhancing the fruit firmness (6.15 kg/cm2) followed by treatment T12S2 i.e. paclobutrazol @ 200 ppm double spray (6.07 kg/cm2). Double spray of prohexadione calcium @ 200 ppm was effective in reducing the vegetative characters and increasing yield and fruit quality characters.

Effect of Achillea millefolium Strips and Essential Oil on the European Apple Sawfly, Hoplocampa testudinea (Hymenoptera: Tenthredinidea)

The European apple sawfly Hoplocampa testudinea (Klug) (Hymenoptera: Tenthredinidae) is a pest in numerous apple orchards in eastern North America. In Quebec, Canada, the European apple sawfly can damage up to 14% of apples and growers use phosphate insecticide during the petal fall stage to control the pest. Since the insecticide is toxic for beneficial insects, we established flower strips of Achillea millefolium L. (Asterales: Asteraceae) to interfere with the oviposition of the insect as an alternative. Populations of European apple sawfly adults were significantly reduced in areas close to flower strips compared to unmanaged areas (natural groundcover). In order to understand the mechanism of the flower strip effect, we tested the repellent effect of A. millefolium essential oil on populations of H. testudinea. Twenty flowers per apple tree were sprayed during full bloom, the oviposition period of the pest. Sprayed and control flowers were then collected and dissected to note the presence of oviposition scars and eggs of the European apple sawfly. Significantly less scars and eggs were observed on sprayed flowers than on control flowers, which means that A. millefolium had a repellent effect on the insect.

Influence of pre-harvest application of gibberellin and brassinosteroid on fruit growth and quality characteristics of pear (Pyrus pyrifolia (Burm.) Nakai) cv. Gola

Quality of fruit crop is an important parameter to decide the acceptability of the product. The present study consists of seventeen year old pear (Pyrus pyrifolia (Burm.) Nakai) trees subjected to seven treatments viz., GA3 (50 ppm,100 ppm), BR (0.5 ppm, 1.0 ppm), and GA3 + BR (50 ppm + 0.5 ppm and 100 ppm + 1 ppm) and water as control, sprayed thrice at 15 days intervals starting from petal fall stage. Each treatment was replicated thrice with one tree served as a treatment unit. The experiment was conducted in Randomized Block Design. The fruits treated with GA3 @ 50 ppm (T1) showed the highest fruit length (6.98 cm), breadth (6.81 cm), weight (175.9 g) and volume (171.16 cc). An improvement in terms of fruit quality was observed either alone or in combined application of GA3 and BR. The application of BR @ 1 ppm (T4) recorded the highest TSS (12.91°Brix) and lowest titrable acidity (0.42%) while the highest ascorbic acid content (6.95 mg / 100 g) and non reducing sugar (0.44%) was estimated under GA3 @ 100 ppm + BR @ 1 ppm (T6). Total sugar (7.88%) and reducing sugar (7.45%) was observed highest in GA3 @ 50 ppm + BR @ 0.5 ppm (T5). Based on this research combined application of GA3 + BR had a positive effect and therefore can be recommended for spray on pear in order to obtain higher yield and better quality.

Foliar application of nitrogen at petal fall stage increases fruit set and size of ‘Bengal’ lychee

Foliar application of nitrogen at petal fall stage increases fruit set and size of ‘Bengal’ lychee

Effect of Application with Gibberellin GA4+7 on Russeting of „Golden Delicious” Apples

Worldwide, the presence of russet on ‘Golden Delicious’ apples has been a concern to producers and marketers of fresh fruit for a long time due to the fact that it decresses the smoothness, perfomes an uniform finish of the fruit and results in economic loss thru quality reduction. Apple cultivars present different degrees of susceptibility to russeting, and fruits in early stages of development are more susceptible than those in later stages. Under orchard conditions, russeting is avoided. For sensitive cultivars the aspect of peel is improved by applying gibberellin GA 4+7. The study subject of the experience was ‘Golden Delicious’ apple variety grafted on M 9. The trees were trained as slender spindles. The distance of plantation is 3.5 x 1.2 m. The tested gibberellic acid was GA 4+7 , (Gerlagib LG). To study russeting of the apple fruits were experimented the following variants of treatment: 1. Control – no treatment; 2. GA 4+7 - 4 mg L -1 ; 3. GA 4+7 - 5 mg L -1 . Trees were sprayed 4 times. The experiment was conducted in the year 2013. During the research, we studied the amount and average of fruits, tree production, firmness of fruits, and  hydrolysis index. Russeting of fruit was estimated at harvest using a grading scale (S. J. Wertheim). It was established that, gibberellic acid GA 4+7 may be included in prevention system of apple fruits russeting with a,  dose of 5 mgL -1 , applied up to 4 times by treatment. First treatment should be performed starting at the beginning of petal fall stage, and the next 3 treatments 7-10 days after previous.

Disease and pest management in apple: Farmers' perception and adoption in J&amp;K state

Diseases and pests are one of the limiting factors for low productivity of the fruit crops in Kashmir valley, India. A study on management of resources with respect to disease and pest management of apple and extent of adoption of recommended plant protection technology was undertaken for increasing apple production in Kashmir valley of J and K State. District Baramulla was selected purposively on the basis of maximum area and production under apple crop. A sample size of 200 apple growers 50 each from 4 villages were selected randomly. The study revealed that the perception index regarding attributes of technology recommended in two diseases viz. San Jose Scale and Apple Scab was 68.88% and 80.76% in respect of profitability (83.97%), simplicity-complexity each 63.57% and 54.27 % for practicability attributes of technology. The data further showed that the farmers adoption level under Chemical control was high at silver tip to green tip stage (80%) and fruit let pea size stage (78%) and medium adoption was observed at pink bloom (bud) stage (74%), petal fall stage (74%) walnut size apple stage (70%) on Apple Scab similarly, the extent of adoption was low (45%) for mechanical and no chemical control measures under clean cultivation. In case of San Jose Scale the farmers adoption level regarding name of chemical, its dose, quantity of water required per acre for preparing spray solution and time of spray at late dormant spray, (feb, March) was high (80%). The findings will help to improve the level of farmers’ knowledge to increase apple production in Kashmir valley.

Response of foliar fertilization of micronutrients on fruit growth and yield in lowchill peach cv. Sharbati

A field experiment was carried out during 2010 and 2011 seasons on seven year old Sharbati cultivar of peach, growing in clay loam soil. The experiment was laid out in randomized block designed to study the effect of foliar spraying of boron, zinc and iron and its combination on fruit growth pattern, yield and yield attributing characters of the low-chill peach. Boric acid (0.1%), zinc sulphate (0.5%) and ferrous sulphate (0.5%) were used as a source of boron, zinc and iron, respectively. All the trees were fertilized with same NPK dose as per recommendation. The spraying was done twice; during last week of February, i.e., after petal fall stage and again at 15 days after the first spraying during both years in three replicates. The result revealed that foliar spraying of peach trees with 0.1 % H3BO3 + 0.5 % ZnSO4, 7H2O + 0.5 % FeSO4, 7H2O was the promising treatment for improvement of fruit growth, fruit length, fruit diameter, fruit volume and firmness of the fruit. This treatment was also found best for maximum fruit retention, average fruit weight as well as the fruit yield.

Relationship Between Plant Phenology andCampylomma verbasci(Hemiptera: Miridae) Damage to Apple Fruit

Damage to apple (Malus domestica Borkhausen) by Campylomma verbasci (Meyer), has occurred even when effective insecticides are applied against nymphs present at the petal fall stage. However, insecticide application at pink bud prevents damage more effectively than when the same insecticides are applied at petal fall. We tested the hypothesis that most mullein bug damage occurs between bloom and petal fall by using two approaches. In the first, we caged naturally occurring nymphs on 'Red Delicious' limbs and restricted their possible infestation timing by applying insecticides both before cages were placed and also through the cage at various crop stages from bloom through fruit set. In a second approach, we caged Red Delicious and 'McIntosh' fruit clusters and introduced either small or large nymphs at various times from bloom through 3 wk after fruit set. Fruit damage on both varieties was greatest when small nymphs were introduced between bloom and petal fall; damage was uncommon from small nymphs introduced after fruit were ≍6 mm, and absent after the 13 mm size. However, damage was greater in cages into which large nymphs were introduced at 10-13 mm, than in untreated control cages. Fruit damage levels were equivalent on McIntosh and Red Delicious. We compared emergence of nymphs from McIntosh shoots with adjacent plantings of other, more susceptible cultivars by forcing hatch in the laboratory from cuttings collected in late winter. Significantly more nymphs hatched from susceptible varieties than from McIntosh, suggesting possible differences in levels of oviposition.

A inibição na síntese de giberelina reduz o crescimento vegetativo em macieiras e proporciona controle de "bitter pit" nos frutos

O "bitter pit" é um distúrbio fisiológico ocasionado pela deficiência de cálcio (Ca) em maçãs. No entanto, trabalhos recentes mostram que o "bitter pit" pode estar relacionado com aumento na atividade de giberelinas nas plantas. Este trabalho teve como objetivo avaliar os efeitos da pulverização de macieiras com um inibidor da síntese de giberelinas, o prohexadiona-cálcio (ProCa), e com giberelina GA3, no crescimento vegetativo das plantas e na ocorrência de "bitter pit". O experimento foi conduzido em um pomar localizado no município de São Joaquim-SC, na safra de 2009/2010. Macieiras 'Catarina' e 'Fuji' foram pulverizadas com água (tratamento-controle), ProCa e GA3 (ambos os produtos na dose de 319 mg L-1), na queda das pétalas (15-10-2009), quando as brotações do ano estavam com 5-10 cm de comprimento, sendo repetidas após 20 dias. Foram feitas avaliações foliares (teor de clorofila, área, massa seca e área específica), em janeiro/2010, e de comprimento dos ramos do ano e de peso dos ramos podados, em maio/2010. Os frutos foram colhidos na maturação comercial, armazenados em câmara fria convencional por quatro meses (0±0,5 ºC/90-95% UR), e então avaliados quanto à ocorrência de "bitter pit" após cinco dias de vida de prateleira. Em ambas as cultivares, o crescimento vegetativo foi significativamente menor nas plantas tratadas com ProCa, e maior naquelas tratadas com GA3, comparativamente ao controle. Maçãs 'Catarina' e 'Fuji' do tratamento com ProCa apresentaram menor ocorrência de "bitter pit" após o período de armazenamento, associada aos menores teores de K, Mg e N, em relação aos teores de Ca, no tecido da casca, comparativamente ao tratamento-controle. Já o tratamento com GA3 aumentou a ocorrência de "bitter pit" em relação ao controle em ambas as cultivares.

Mechanical String Thinner Reduces Crop Load at Variable Stages of Bloom Development of Peach and Nectarine Trees

Thinning of blossoms or fruitlets is a labor-intensive requirement in the production of peach and nectarine (Prunus persica) fruit of optimum size and quality. Prior research conducted by the authors on string blossom thinners for managing peach tree crop load demonstrated that this new technology reduces labor requirement and improves fruit size. The research reported in the current article was conducted over 2 years on ‘Sugar Giant’ peach and ‘Arctic Sweet’ nectarine to evaluate string blossom thinner efficacy at variable stages of bloom development ranging from pink to petal fall. Blossom removal at the pink stage of bloom development was lower than at other stages in 2008; however, a 150-rpm versus 120-rpm spindle rotation speed resulted in blossom removal similar to the 80% full bloom (FB) treatment in 2009. Blossom removal at the petal fall stage was similar to the open bloom stage with the exception of the 2009 ‘Sugar Giant’ trial, in which blossom removal was higher at 80% FB. Flower density and fruit set of the bloom stage compared with hand-thinned control treatments followed a similar trend with the exception that there were fewer differences in 2009 and in lower canopy regions. Follow-up hand thinning time was reduced by all string thinning/year combinations except ‘Arctic Sweet’ at pink in 2008 and 2009 and at petal fall in 2009. The best treatments reduced follow-up hand thinning time compared with green fruit hand thinning alone by 51% and 41% for ‘Sugar Giant’ and by 42% and 22% for ‘Arctic Sweet’ in Years 1 and 2, respectively. In 2008, the percentage of fruit in the “7.0 cm or greater” size category was increased by all bloom stage treatments in both cultivars. The 2009 size distribution of ‘Arctic Sweet’ fruit was unaffected, but the percentage of ‘Sugar Giant’ fruit in higher market value size categories was increased by the 80% FB and higher rpm pink treatments. Savings in hand thinning time and/or increases in fruit size in both years associated with the bloom stage treatments resulted in a net positive impact of $123/ha to 1368/ha compared with hand thinning alone.

Blooming phenology and self-incompatibility of some commercial cherry ( Prunus avium L.) cultivars in Iran

Self-sterility in cherry ( Prunus avium L.) is one of the most important problems in commercial cherry orchards in Iran and many other countries. The main objective of this research was to determine self-fertility rate and blooming phenology of 25 commercial cherry ( P. avium L.) cultivars in Iran. This study was conducted during 2006–2007. Results revealed that the stage of bud swell in all cultivars began late second decade of March, which lasts 8–11 days. In all cultivars the duration end bloom to petal fall stage took 5 days. Cherry cultivars were classified into three groups considering their overlapping pollination. The cultivars each group had a great overlapped pollination toward each other. The results also showed that there was a significant difference among cultivars in respect of the fruit set ( P < 1%). The fruit set of open pollination treatment among the cultivars varied in range of 7.36–41.58%. However fruit set was not observed in isolated pollination (artificial and natural self-pollination). In open pollination, the cultivars were also classified into four groups, i.e. weak fertility (Moreau and Ferracida), mean fertility (Siah Mashhad, Napelon, Proteva, Haj usefy, Lambert, Roshun, Sefid Ghermeze Baghno, Arak, Belamarka, Siah Shabestar, Ghermeze Rezaeyeh, Abardeh, Soraty Lavisan and Victoria), good fertility (Peshrase Mashhad, Dovoumras Mashhad, Bing, Shesheiy Mashhad, Siah Ghazvin and Sefid Rezaeyeh), very good fertility (Zarde Daneshkadeh, Dirrase Italia and No. 1 karaj). All cultivars were found to need cross-pollination and included in self-sterile group.

FOLIAR APPLICATION OF CALCIUM AND BORON INFLUENCES PHYSIOLOGICAL DISORDERS, FRUIT YIELD AND QUALITY OF STRAWBERRY (F. × ANANASSA DUCH.)

Studies were conducted to determine the influence of pre-harvest foliar application of Ca, B and their combination on physiological disorders, fruit yield and quality of strawberry. The treatments consisted of (i) five sprays of calcium as CaCl 2 (first spray was performed at the petal fall stage and later at 7 days interval), (ii) three sprays of boron as boric acid (first spray at the beginning of flowering and later at 15 day interval), (iii) combination of (i) and (ii), and (iv) plants sprayed with water served as the control. Results indicated that fruit harvested from plants, which were sprayed either with Ca or Ca+B had lesser incidence of albinism and grey mould significantly than those harvested from plants sprayed either B alone or not treated. Although, B alone could not influence the incidence of albinism and grey mould, it reduced fruit malformation significantly. Further, pre-harvest application either of Ca or B or Ca+B could not influence the average berry weight and total fruit yield but marketable fruit yield differed significantly among the treatments. The lowest marketable fruit yield was recorded in plants under control, and the highest in plants sprayed with Ca+B (20% higher compared to control). Similarly, fruit receiving Ca or Ca+B were firmer had lower TSS, higher acidity and ascorbic acid content at the time of harvest and storage for 5 days (10°C and 90% RH) than those harvested from plants under control. Our studies clearly indicated that sequential foliar application of Ca+B can be recommended for reducing the incidence of albinism, malformation and grey mould in strawberry, and to get higher marketable yield.